Experimental study on growth law of the parallel cracks in the surrounding rock of roadway under explosion load

Abstract：The damage of the surrounding rock of roadway under explosion load is often manifested as the growth and penetration of the cracks in the surrounding rock.In order to deeply understand the growth process and mechanism of original crack in the surrounding rock under the adjacent explosion load and put forward specific protective measures, the experimental system of digital laser dynamic caustic line was adopted to research the penetration process of both parallel cracks.The results showed that the explosion source, the free surface of the roadway and the interaction of original cracks were the main factors affecting the crack growth and penetration process.The growth of the crack in the surrounding rock under the adjacent explosion load was mainly characterized by the penetration between the explosion crack and the original crack, and the penetration among the original cracks.The transfer of energy was accompanied during the penetration process.Under the explosion load, the explosion crack from the explosion source penetrated the crack in the surrounding rock, and continued to grow along growth direction of original explosion crack, i.e.the radial direction of the blasthole.Meantime the main line of explosive energy release was formed, and the energy release of other weak areas would be significantly weakened.When the two original cracks had an interaction zone in the adjacent tip, the original crack farther away from the explosion source growed towards to the original crack, which was closer to the explosion source.

Keyword：explosion load;surrounding rock of roadway;original crack;growth law;dynamic caustics method;